1. Field of the Invention
The present invention relates to the reading of previously recorded images in applications in which the images are restituted by successive reading frames each corresponding to one image, as is more particularly the case with video images.
In an application which is preferred but not considered in any limiting sense, the primary aim of the invention is to utilize the facilities of selection of images of recordings on videodisks for varying the apparent rate of displacement of images at the time of reading. Thus, when reading a moving scene previously recorded on a videodisk, it becomes possible to vary the impression of speed gained by an observer who is viewing the displayed images. For example, a driving simulator can then be controlled by restitution of a landscape which is moving past in front of a driver by controlling the rate of displacement of the landscape as a function of the driving speed simulated by the driver.
2. Description of the Prior Art
Videodisk readers in current use are so designed as to permit selection of the image to be restituted at each reading frame by a periodic process which is capable of skipping or repeating images, for example one image out of two. It is not proposed in this process to utilize this capacity for varying the speed of representation of a moving scene with respect to a nominal speed which corresponds as a rule to a constant reference speed used as a basis for recording. A fortiori, no arrangements are made for permitting a continuous and progressive variation of this speed as is necessary in particular for driving simulators. In point of fact, even assuming that the reader is controlled so as to skip one image out of two, for example, this would lead to no more than a stepwise increase in speed without permitting a progressive and jerk-free variation as contemplated by the invention since it is imperative to ensure that the same time of reading of an image by a video scanning frame is always maintained.